Right-wing extremist Anders Behring Breivik said he won’t appeal the prison sentence handed to him on Friday, and apologized for not killing more people in the bomb and gun massacre that left 77 people dead.

Prosecutors have not decided yet whether to appeal the court ruling that came down on Friday, which declared Breivik sane enough to be held criminally responsible for attacks "unparalleled in Norwegian history."

"Since I don't recognize the authority of the court I cannot legitimize the Oslo district court by accepting the verdict," Breivik said. "At the same time I cannot appeal the verdict, because by appealing it I would legitimize the court."

Earlier on Friday, the confessed mass killer smiled in apparent victory at court ruling, which declared the right-wing extremist sane enough to be held criminally responsible for attacks "unparalleled in Norwegian history” on July 22, 2011

Prosecutors had sought an insanity ruling, which would have helped advance their argument that the murders were the work of a mad man, not a reasoned retaliation against Muslim influence in Norway, as Breivik maintains.

"Anders Breivik had confessed to the crimes. He said he had carried them out so that was never in doubt, but what was in doubt was how the prosecution would come back," David MacDougall, a senior producer with The Associated Press told CTV’s Canada AM.

"The prosecution wanted Anders Breivik to be found insane, therefore a psychiatric institution would by his punishment. However the judges came back and said he's legally sane, he's sane enough to be held criminally responsible."

Breivik had said through his lawyers before the ruling that he would appeal any decision that found him insane, a move that would have meant a second 10-week trial.

Breivik has defended his actions throughout his trial, and the decision reinforces his argument that the murders were the actions of a political terrorist rather than a psychotic killer.

"He didn’t want to be seen as just an insane mad man who carried out these acts, and to be consigned to history as a mad man with a gun," MacDougall said.

He added: "He wanted to be found sane because then his actions, he feels, are justified."

Since his arrest, Breivik has said the attack was meant to draw attention to the immigration problems plaguing Norway and to inspire other extremists to rise up as "militant nationalists" across the continent.

Friday's ruling by a five-judge panel means Breivik he will likely go to prison for the maximum 21-year sentence available to prosecutors, though he was officially sentenced to between 10 and 21 years. However, the sentence can be extended beyond 21 years by five-year increments if Breivik is still considered to be a threat to the public. As a result, most experts say he will likely never be released.

Prosecutors had argued Breivik was insane as he plotted the killings as a means of drawing attention to a manifesto he wrote, blaming Muslim immigrants for problems in Europe.

Breivik, however, had said authorities were portraying him as insane in order to taint his political views.

Breivik, 33, was unanimously convicted by the five-judge panel of terrorism and premeditated murder.